Flexible pump based on dielectric elastomer material

ABSTRACT

A flexible pump comprises: a flexible pump balloon comprising multiple non-stretchable tubular flexible films that have a shuttle-shaped cross-section, are arranged in a ring array, and are spliced adjacently, a middle section of each tubular flexible film being a fill area saturated with a liquid medium with high breakdown strength, and a positive electrode and a negative electrode being fixed on a surface of one side of the middle section of each tubular flexible film in a radial direction and symmetrically located on two sides of an axial reference plane of the middle section respectively; and a pair of rigid end covers. The flexible pump solves the technical problems of liquid transport and pressurization.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority of Chinese Application No. 202110649740.8, filed Jun. 10, 2021, the contents of which are all incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION 1. Technical Field

The invention relates to a pump, in particular to a flexible pump based on a dielectric elastomer material.

2. Description of Related Art

With the development of the biomimetic technology, further integrated and elaborated mechanical techniques are receiving more and more attention. The driving performance of integrated and elaborated mechanical equipment is of great importance. The requirements for driving reliability, moving continuity, response speed and precision are extremely strict.

Hydraulic drive, as one of the important drive modes, is featured by low speed, steady, high drive power, overload protection, flexible drive configuration, and the like. Pumps, as the core of hydraulic drive, are used for delivering or pressurizing fluid. Common pumps on the market are made of metal materials and have been widely used in the field of industrial automation.

However, common metal pumps have the following problems:

(1) Rigid components generally have a limited degree of freedom, which restrains the moving flexibility of the pumps;

(2) Under the influence of working conditions, the metal pumps may break down due to corrosion, cavitation, scouring and abrasion, a large amount of money has to be spent in purchasing new pumps, and a large number of parts are discarded, resulting in serious capital and material waste;

(3) The metal pumps are complicated in structure, large in size, high in weight, inconvenient to move and carry, thus having limitations when applied to some precision fields such as the biomedical field;

(4) The production cost of metal is high.

All these problems limit, to some extent, the development of metal materials in this field.

BRIEF SUMMARY OF THE INVENTION

To overcome the defects of the prior art, the invention improves traditional metal pumps in material and structure and develops a flexible hydraulic pump based on the deformation principle of a dielectric elastomer material to deliver and pressurize fluid.

To fulfill the above objective, the invention designs a flexible pump based on a dielectric elastomer material, which structurally comprises: a flexible pump balloon comprising multiple non-stretchable tubular flexible films which have a shuttle-shaped cross section, arranged in a ring array and spliced adjacently, a middle section of each tubular flexible film being a fill area saturated with a liquid medium with high breakdown strength, and a positive electrode and a negative electrode being fixed on a surface of one side of the middle section of each tubular flexible film in a radial direction, located on two sides of an axial reference plane of the middle section respectively, and distributed symmetrically; and a pair of rigid end covers provided with a water inlet and a water outlet respectively and located at two ends of the flexible pump balloon separately, same sides of the multiple tubular flexible films being fixed to the corresponding cover one by one.

The working principle of the flexible pump is as follows:

The flexible pump starts to work; when a voltage is applied to the positive electrodes and the negative electrodes on all the tubular flexible films, the positive electrodes and the negative electrodes are closed gradually under the action of electrostatic force, and liquid wrapped in the sides, covered with the positive electrodes and the negative electrodes, of the films in the radial direction is squeezed to flow to the sides not covered with the positive electrodes and the negative electrodes, so that the shuttle-shaped cross-section of all the tubular flexible films bulges to form a circular cross-section; because the tubular flexible films are non-stretchable, the total perimeter of the flexible pump balloon is decreased, the volume of an inner cavity of the flexible pump balloon is decreased; and the perimeter of the rigid end covers on the two sides remains unchanged when the flexible pump balloon contracts, upper and lower sections, not filled with the liquid medium, of each tubular flexible film contract in the axial direction, and finally, liquid in the inner cavity of the flexible pump balloon is compressed to flow out via the water outlet in one rigid end cover;

On the contrary, when no voltage is applied to the positive electrodes and the negative electrodes, the electrostatic force on the positive electrodes and the negative electrodes disappears instantly, the liquid medium is driven by liquid pressure to flow back from the sides, not covered with the positive electrodes and the negative electrodes, of the films, and the circular cross-sections of the tubular flexible films gradually returns to the shuttle-shaped cross-section; similarly, because the films are non-stretchable, the total perimeter of the flexible pump balloon is increased, and the upper and lower sections, not filled with the liquid medium, of the tubular flexible films stretch synchronously in the axial direction, so that the volume of the inner cavity of the flexible pump balloon is increased, the pressure in the inner cavity of the flexible pump balloon is decreased, and liquid flows in via the water inlet in the other rigid cover.

Based on the above solution, the invention may be improved in the following aspects:

Preferably, the electrodes are ionically conductive hydrogel electrodes. The hydrogel electrodes are soft, the films wrapping the liquid medium can deform greatly during operation of the flexible pump, and the soft hydrogel electrodes can better fit the films and will not abrade the films, so that liquid wrapped in the films will not leak.

Preferably, the liquid medium filled in the non-stretchable tubular flexible films is a plant-based oil with high breakdown strength. When electrostatic force is needed, the requirements for an electric field are extremely high, and a voltage of several thousand volts is needed, which means that a liquid medium with a high dielectric constant should be used to avoid breakdown, which may otherwise cause oil leakage.

Preferably, one-way valves in the water inlet and the water outlet may be membrane valves of a single-membrane, double-membrane or multi-membrane structure, so that the structure is simplified, and liquid can flow in and flow out in one direction.

Further, as an improvement of the above preferred solution, the one-way valves in the water inlet and the water outlet may be of an anti-backflow valve structure. According to the valve structure, for preventing blood flowing back, in the heart, when blood flows forward, the valve is opened; when the blood flows reversely, the valve is closed. Anti-backflow valves are made with reference to the principle of such a structure and are disposed in the water inlet and the water outlet to ensure that fluid flows in one direction. The structure is simple, and using is convenient and fast.

The solution has the following advantages: first, compared with metal materials, the flexible pump is made of a flexible material, which has the properties of elasticity, adaptability and shock absorption, can deform greatly and has good environmental adaptability; second, the pump made of the flexible material is light, easy to carry and move, lower in cost, easy to manufacture, and free of corrosion and cavitation; in addition, when not used, the flexible pump can be stored after liquid in the inner cavity of the pump balloon is discharged.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a first overall structural diagram of a flexible pump when no voltage is applied;

FIG. 2 is a schematic diagram of the working principle of an anti-backflow valve structure in a water inlet;

FIG. 3 is a schematic diagram of the working principle of an anti-backflow valve structure in a water outlet;

FIG. 4 is a schematic diagram of the deformation principle of a dielectric elastomer material;

FIG. 5 is a schematic diagram of the extended length of the dielectric elastomer material;

FIG. 6 is a top view of a middle section of a balloon structure of the flexible pump when no voltage is applied;

FIG. 7 is a top view of the middle section of the balloon structure of the flexible pump when a voltage is applied;

FIG. 8 is an overall structural diagram of the flexible pump when a voltage is applied;

FIG. 9 is a second overall structural diagram of the flexible pump when no voltage is applied.

In the figures: 1, water inlet; 2, upper end cover; 3, flexible pump balloon; 4, lower end cover; 5, water outlet; 6, valve structure; 7, liquid medium; 8, tubular flexible film; 9, positive electrode; 10, negative electrode; 11, upper section; 12, lower section.

DETAILED DESCRIPTION OF THE INVENTION

The technical solutions of the embodiments of the invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments. Obviously, the embodiments in the following description are merely illustrative ones, and are not all possible ones of the invention. All other embodiments obtained by those ordinarily skilled in the art based on the following ones should fall within the protection scope of the invention.

As shown in FIG. 1 , as one implementation of the invention, this embodiment provides a flexible pump based on a dielectric elastomer material, comprising a water inlet 1, an upper end cover 2, a non-stretchable flexible pump balloon 3, a lower end cover 4, and an water outlet 5, wherein the upper end cover 2 and the lower end cover 4 are disposed at an upper end and a lower end of the flexible pump balloon 3 respectively and are in seal connection with the flexible pump balloon 3 through a sealant.

As shown in FIG. 2 and FIG. 3 , a flexible anti-backflow valve structure 6 is disposed on an edge of the interior of the water inlet 1, which is similar to a valve structure 6 for preventing blood from flowing back in the heart. When liquid in the flexible pump balloon 3 is about to flow out via the water inlet 1, the valve structure is in a closed state, as shown in FIG. 2(a), so water in the flexible pump balloon 3 cannot flow out. When water in the outside is about to flow into the flexible pump balloon 3, as shown in FIG. 2(b), the pressure in the outside is higher than the pressure in the flexible pump balloon 3, and the valve structure is in an open state, so water in the outside is pumped into the flexible pump balloon 3. Similarly, a flexible anti-backflow valve structure 6 is disposed on an edge of the interior of the water outlet 5. When liquid in the outside is about to flow into the flexible pump balloon 3, the valve structure is in a closed state, as shown in FIG. 3(a), so the liquid in the outside cannot enter the flexible pump balloon 3 via the water outlet 5. When liquid in the flexible pump balloon 3 is about to flow out, as shown in FIG. 3(b), the pressure in the flexible pump balloon 3 is higher than the pressure in the outside, and the valve structure is in an open state, so liquid in the flexible pump balloon 3 is pumped out.

As shown in FIG. 4 , the flexible pump balloon 3 is mainly composed of four parts, which are a liquid medium 7, a non-stretchable rectangular flexible film, positive electrodes 9 and negative electrodes 10 respectively. Because the flexible pump driven by means of the deformation principle of a dielectric elastomer requires a high electric field, the liquid medium 7 is a plant-based oil with high breakdown strength. The non-stretchable rectangular flexible film is a biaxially oriented polypropylene film which has good mechanical strength and high dielectric breakdown strength, so that the reliability in use is guaranteed. The positive electrodes 9 and the negative electrodes 10 are ionically conductive hydrogel electrodes. The hydrogel electrodes are flexible, can deform to a large extent to better fit the non-stretchable rectangular flexible films when the flexible pump works, and will not abrade the film, so that the film will not be damaged, and leaking of the liquid medium 7 is avoided. The specific manufacturing process is as follows: first, the non-stretchable rectangular flexible film is sealed through a hot press and a heating metal mold to make multiple non-stretchable tubular flexible films 8, which have a shuttle-shaped cross-section, are distributed in a ring array and are spliced together adjacently, a middle section of each tubular flexible film 8 is a fill area, and a gap is reserved in a seal boundary of each fill area to allow the liquid medium 7 to be filled in the fill area. After the fill areas are saturated with the liquid medium 7, the gaps are completely sealed with heated aluminum strips. Finally, prefabricated hydrogel electrodes are adhered to a half side of the middle section of each tubular flexible film 8.

As another implementation of the invention, the specific structure of the flexible pump balloon 3 of the flexible pump may be as shown in FIG. 9 , and the specific manufacturing process is as follows: first, multiple non-stretchable tubular flexible films 8 are sealed through a hot press and a heating metal mold, wherein the tubular flexible films 8 are polypropylene films, a middle section of each tubular flexible film 8 is a fill area, and a gap is reserved in a seal boundary of each fill area to allow the liquid medium 7 to be filled in the fill area. Next, the fill areas are saturated with the liquid medium 7, and then the gaps are completely sealed with heated aluminum strips. Then, the multiple tubular flexible films 8 are arranged in a ring array and are adjacently hot-pressed to be spliced through the hot press and the heating metal mold. Finally, prefabricated hydrogel electrodes are adhered to one side of the middle section of each tubular flexible film 8.

The deformation principle of the dielectric elastomer material is as follows: when power is not supplied, as shown in FIG. 4 (a), the liquid medium 7 is wrapped in the non-stretchable tubular flexible films 8, and one side of each tubular flexible film 8 is covered with the positive electrode 9 and the negative electrode 10, and the other side of each tubular flexible film 8 is not covered with the electrodes. When a voltage V₂ is applied to the electrodes, the positive electrodes 9 and the negative electrodes 10 are closed gradually under the action of electrostatic force, and the liquid medium 7 wrapped in the sides, covered with the positive electrodes 9 and the negative electrodes 10, of the tubular flexible films 8 is squeezed and flows to the sides, not covered with the electrodes, of the tubular flexible films 8. As shown in FIG. 4(b), when squeezed by the positive electrodes 9 and the negative electrodes 10, the flat shuttle-shaped cross-section bulges gradually. As shown in FIG. 4(c), when the liquid medium 7 is completely squeezed from the sides, covered with the positive electrodes 9 and the negative electrodes 10, of the tubular flexible films 8 to the sides, not covered with the positive electrodes 9 and the negative electrodes 10, of the tubular flexible films 8, the cross-section becomes circular. When voltage application is stopped, the electrostatic force disappears, the liquid pressure of the sides not covered with the positive electrodes 9 and the negative electrodes 10 is higher than the liquid pressure of the sides covered with the positive electrodes 9 and the negative electrodes 10, liquid flows from the high pressure to the low pressure, the liquid medium 7 gradually flows from the sides not covered with the positive electrodes 9 and the negative electrodes 10 to the sides covered with the positive electrodes 9 and the negative electrodes 10, and the circular cross-section turns into the flat shuttle-shaped cross-section again. As shown in FIG. 5 , if the length of each tubular flexible film 8 is 2L₀, when no voltage is applied, the cross-section is flat, and the length of each section of the dielectric elastomer is approximate to 2L₀. When the voltage V₂ is applied, the positive electrodes 9 and the negative electrodes 10 are closed under the action of electrostatic force, and the flat shuttle-shaped cross-section turns into the circular cross-section; because the films are non-stretchable, the total length of each section of the dielectric elastomer is L₀+2L₀/π, so the total length of the dielectric elastomer is decreased. Similarly, when voltage application is stopped, the length of each section of the dielectric elastomer returns to 2L₀ again under the action of liquid pressure.

As shown in FIG. 6 , the dielectric elastomer material is arranged in a circular shape to form the non-stretchable flexible pump balloon, and fluid/liquid to be transported or pressurized is wrapped in the pump balloon. As shown in FIG. 7 , when a voltage is applied, the total length of the dielectric elastomer is deceased according to the deformation principle of the dielectric elastomer material, that is, the total perimeter of the flexible pump balloon 3 is decreased, so the total volume of the flexible pump balloon 3 is decreased. Similarly, when no voltage is applied, the dielectric elastomer returns to the original length under the action of liquid pressure based on the deformation principle of the dielectric elastomer material, that is, the total perimeter of the flexible pump balloon 3 is increased, so the total volume of the flexible pump balloon 3 is increased.

When no voltage is applied, the overall structure of the flexible pump is shown in FIG. 1 . After a voltage is applied, the positive electrodes 9 and the negative electrodes 10 are closed gradually under the action of electrostatic force, liquid wrapped in the sides, covered with the positive electrodes 9 and the negative electrodes 10, of the non-stretchable tubular flexible films 8 is squeezed and flows to the sides not covered with the electrodes, so the flat shuttle-shaped cross-section bulges to form a circular cross-section, as shown in FIG. 8 . Because the tubular flexible films 8 are non-stretchable, the total perimeter of the flexible pump balloon 3 is decreased, so the volume of an inner cavity of the flexible pump balloon is decreased. A section of each non-stretchable tubular flexible film 8 above the flexible pump balloon filled with liquid and a section of the non-stretchable tubular flexible film 8 below the flexible pump balloon filled with liquid are not filled with the liquid medium 7. Because the perimeter of the upper end cover 2 and the perimeter of the lower end cover 4 remain unchanged, upper sections 11 and lower sections 12 of the non-stretchable tubular flexible films 8 contract in the axial direction of the pump balloon, so that liquid in the inner cavity of the pump balloon is further compressed. Under the action of the valve structure 6, liquid will not flow out via the water inlet 1 in the upper end cover 2 and can only be pumped out via the water outlet 5 in the lower end cover 4. When no voltage is applied to the electrodes, the electrostatic force disappears, the pressure of the liquid medium 7 wrapped in the sides, not covered with the electrodes, of the films is higher than the pressure of the liquid medium 7 wrapped in the sides, covered with the electrodes, of the films, and the liquid medium 7 is driven by the liquid pressure to flow back, so that the circular cross-section gradually turns back into the flat cross-section; and because the films are non-stretchable, the total perimeter of the flexible pump balloon 3 is increased, the volume of the inner cavity of the pump balloon is increased, the pressure in the inner cavity of the pump balloon is decreased, and under the action of the valve structure 6, the liquid cannot flow into the inner cavity of the pump balloon via the water outlet 5, and water in the outside can be pumped into the inner cavity of the pump balloon via the water inlet 1. By applying and interrupting the voltage repeatedly according to the above process, the flexible pump unceasingly pumps liquid into the pump balloon via the water inlet 1 and pumps out liquid via the water outlet, so that liquid transport and pressurization are realized.

The invention is not limited to the above optimal implementations, and products in other forms obtained under the enlightenment of the invention should fall within the protection scope of the invention as long as their technical solutions are identical with or similar to the technical solutions of the invention regardless of any variations in shape or structure. 

What is claimed is:
 1. A flexible pump based on a dielectric elastomer material, comprising: a flexible pump balloon comprising multiple non-stretchable tubular flexible films that have a shuttle-shaped cross-section, are arranged in a ring array, and are spliced adjacently, a middle section of each said tubular flexible film being a fill area saturated with a liquid medium with high breakdown strength, and a positive electrode and a negative electrode being fixed on a surface of a side of the middle section of each said tubular flexible film in a radial direction, located on two sides of an axial reference plane of the middle section respectively, and distributed symmetrically; and a pair of rigid end covers provided with a water inlet and a water outlet respectively and located at two ends of the flexible pump balloon separately, same ends of the multiple tubular flexible films being fixed to the corresponding rigid end cover one by one.
 2. The flexible pump based on a dielectric elastomer material according to claim 1, wherein the tubular flexible films are biaxially oriented polypropylene films.
 3. The flexible pump based on a dielectric elastomer material according to claim 1, wherein the liquid medium is a plant-based oil with high breakdown strength.
 4. The flexible pump based on a dielectric elastomer material according to claim 1, wherein the positive electrodes and the negative electrodes are ionically conductive hydrogel electrodes.
 5. The flexible pump based on a dielectric elastomer material according to claim 1, wherein the water inlet and the water outlet in the rigid end covers are both of a valve structure. 